A nutritional relationship of longstanding interest and investigation has been that between vitamin E and selenium. This proposal would explore the biological implications of that relationship in the nonhuman primate through study of a vitamin E/selenium responsive spontaneous hemolytic anemia in a unique animal model, the owl monkey. The anemia is a life-threatening entity for the owl monkey, a species already identified as a valuable model for viral-induced cancer. The anemia is partially responsive to vitamin E injection, but more responsive to combined injection of vitamin E and selenium. To determine its pathogenesis and whether the anemia results from a peculiarity of the RBC glutathione peroxidase system or inherent RBC susceptibility to peroxidative damage, RBC membrane lipids will be characterized and peroxidative index estimated by malondialdehyde determination. In addition, RBC glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and reduced glutathione will be determined. Qualitative and quantitative estimates of the dietary requirements for selenium and vitamin E will explore the precise etiology of the vitamin E/selenium-responsive anemia. These data will be meaningful from at least three points of view: 1) they will provide a data base for establishing satisfactory dietary levels for the maintenance of a valuable nonhuman primate, the owl monkey, in captivity; 2) they will allow identification and development of a potential model for more exacting determination of the vitamin E/selenium interrelationship in the primate; 3) they should identify the potential of the owl monkey as a model for the vitamin E/selenium-responsive anemia of the premature human infant.